# CVE-2026-29643: Denial of service in n/a

> A local attacker can cause a denial of service and inconsistent state in the XiangShan RISC-V processor by triggering improper exception handling in the CSR subsystem.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Apr 2026
- **Updated:** 21 Apr 2026
- **Also known as:** GHSA-6pg9-3wf4-7w8v

## What is CVE-2026-29643?

CVE-2026-29643 is a high-severity denial of service vulnerability in n/a, published on 20 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

XiangShan (Open-source high-performance RISC-V processor) commit edb1dfaf7d290ae99724594507dc46c2c2125384 (2024-11-28) contains an improper exceptional-condition handling flaw in its CSR subsystem (NewCSR). On affected versions, certain sequences of CSR operations targeting non-existent/custom CSR addresses may trigger an illegal-instruction exception but fail to reliably transfer control to the configured trap handler (mtvec), causing control-flow disruption and potentially leaving the core in a hung or unrecoverable state. This can be exploited by a local attacker able to execute code on the processor to cause a denial of service and potentially inconsistent architectural state.

Weakness: CWE-703 (Improper Check or Handling of Exceptional Conditions)

## Which versions are affected by CVE-2026-29643?


## How do I fix CVE-2026-29643?

No fix has been published for CVE-2026-29643 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-29643 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-29643 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29643 and fix it if it is affected.

What it is: CVE-2026-29643 is a high-severity denial of service vulnerability in n/a, published on 20 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-29643 exists.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-29643/ (Markdown: https://insights.sbomify.com/CVE-2026-29643/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29643
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29643
- OSV: https://osv.dev/vulnerability/CVE-2026-29643

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29643/
Summaries are generated and may contain mistakes; the official description above is the record.